Optimal Adaptive Protection of Active Distribution Networks Using Optimized Selection of Standard Characteristics for Directional Overcurrent relays Considering Limits of Setting Groups’ Number

The changes in configurations of distribution networks due to the outages of any upstream substations or distributed generations (DGs) is one of the essential challenges in the design of distribution systems. The changes in topologies of the network affect the protective schemes and might lead to coordination constraint violations in different operation modes and configurations. It is inevitable to appear some coordination constraint violation if only the base grid-connected operation mode and configuration is considered in the optimal protection settings. The adaptive protective schemes have several advantages compared to those using only one setting group, and their speed would be more desired. Although different research works have been done in the literature in adaptive protective schemes, there is a research gap about considering the limited number of setting groups for directional overcurrent relays (DOCRs), besides other aspects of active distribution networks and adaptive schemes. This research tries to fill such a research gap by proposing a new optimized adaptive protection system, considering various network configurations, by the limited number of setting groups. Since the proposed optimal settings for DOCRs are applied to a limited number of setting groups, it would be practical. Optimizing the standard relay characteristics in the proposed method is another contribution. Test results of applying the introduced method on the distribution portion of the IEEE 30-bus test system highlight the advantages of this study. Simulation results infer that 54.27% improvement in operating time of the protection system is achievable through applying the proposed method compared to available adaptive ones because of optimizing the relay characteristics.